package c_021;

import java.util.LinkedList;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

/**
 * 面试题：写一个固定容量同步容器，拥有put和get方法，以及getCount方法
 * 能够支持两个生产者线程以及10个消费者线程的阻塞调用
 *
 * 使用Lock和Condition来实现
 * 对比两种方式，condition的方式可以更加精确的指定哪些线程被唤醒
 * notifyall的唤醒是由JVM选择的
 *
 */
public class MyContainer2<T> {
    final private LinkedList<T> lists=new LinkedList<T>();
    final private int MAX=10;   //最多10个元素
    private int count=0;

    private Lock lock=new ReentrantLock();
    /*绑定到condition中-->更有针对性   */
    private Condition producer=lock.newCondition();
    private Condition consumer=lock.newCondition();

    public void put(T t){
        lock.lock();
        try {
            while (lists.size()==MAX){  //想想为什么用while而不是用if

                /*Causes the current thread to wait until it is signalled or interrupted.*/
                producer.await();
            }
            lists.add(t);
            ++count;
            consumer.signalAll();//通知消费者线程进行消费
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            lock.unlock();
        }
    }

    public T get(){
        T t=null;
        lock.lock();
        try {
            while (lists.size()==0){
                consumer.await();
            }
            t=lists.removeFirst();
            count--;
            producer.signalAll();   //通知生产者进行生产
        } catch (InterruptedException e) {
            e.printStackTrace();
        } finally {
            lock.unlock();
        }
        return t;
    }

    public static void main(String[] args) {
        MyContainer2<String> c =new MyContainer2<>();



        //启动消费者线程
        for (int i = 0; i < 10; i++) {
            new Thread(()->{
                for (int j = 0; j < 5; j++) {
                    System.out.println(c.get());
                }
            },"c"+i).start();
        }

        try {
            TimeUnit.SECONDS.sleep(2);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        //启动生产者线程
        for (int i = 0; i < 2; i++) {
            new Thread(()->{
                for (int j = 0; j < 25; j++) {
                    c.put(Thread.currentThread().getName()+" "+j);
                }
            },"p"+i).start();
        }
    }
}